Carry handles for electronic instruments are normally desired to be lightweight, relatively rigid, and comfortable. A typical handle has an elongated grip with a hollow tube providing structural support, and an overmolded elastomeric coating for user comfort. The cores of such hollow handles may be formed by gas assist molding, in which air is introduced into the plastic molding process to provide a hollow chamber. While effective, gas assist molding has the disadvantage of being relatively expensive compared to conventional injection molding. In addition, the process is too sophisticated for many manufacturers, limiting the available sources for such parts.
An alternative to gas assist molding for forming hollow parts is to form such parts in two pieces, and assemble them to provide a hollow part. This is feasible in some applications. However, multi-part construction is normally not suitable for parts that require overmolding with an elastomeric layer. The overmolding process involves placing the molded handle into a larger mold, and injecting elastomer into the void between the handle and the mold to provide a conforming elastomer layer. The pressures involved in the overmolding process may crush the core part if it lacks sufficient structural integrity, and any gaps between the components can allow an unwanted incursion of elastomer into the hollow chamber. Moreover, even if the core is adequately sealed against incursion of elastomer, even minimal gaps or seams allow pressurized gas to get trapped inside the part during overmolding process. This pressurized gas then can cause bubbling or delamination of the overmolded material when the part is released from the pressure of the mold, as the gas attempts to expand.